I have an 04 expedition that has a grinding noise, and vibration that only happens around 1300-1800 RPM, when the truck is in gear, any gear any speed. I hear the noise off idle under partial throttle, and feel the vibration in the accelerator. It is most prevalent at low speeds, worst when leaving from a stop, but also occurs at highway speeds. Any input would be greatly appreciated. Just want to get some general ideas before i tear into the truck searching blindly.

 

You say any gear, does it happen when stationary if you revv it to the rpm you mentioned?

 

I suspect one or more bad u-joints.

 

No dose not happen when in park. Only when moving.

 

There is also a slight hesitation when downshifting at highway speeds... No hard shifty just takes longer, and more throttle movement than expected. May be unrelated though.

 

Sounds like me ignition related like a bad coil over plug or spark plug. Check those things out, might be as simple as moister on one of the spark plug holes.

 

Just installed new plugs and coils about a month ago, had a intermittent miss and rough idle, those are gone, but the vibration and hesitation on down shift remain... A buddy suggested it could be vacuum related... But I have checked to the best of my abilities and have not found any leaks... I'll check the u joints in the morning.

 

Keep in mind that the only way to check u-joints is with the driveshaft removed from the truck.

 

Did a quick check of the u joints... There is no movement, or play when trying to turn the driveshaft by hand and holding the yoke with the other hand... Was told this was a quick way to check if there was an issue... Do they maybe just need to be greased? Last oil change I was busy and didn't have time to do it myself...must admit I went to jiffy lube... Maybe they didn't grease them like they claimed they would... Idk thanks for the help so far guys any additional input would be greatly appreciated.

 

All that checks is that neither one has broken and the driveshaft hasn't fallen out of the truck. I think you have one or more bad u-joints. There is no way to check that with the driveshaft installed in the truck.

 

There's a special grease ford used on the slip yolk that once it dries out you will get a vibration on acceleration, might want to look into that.